"Scientists are using carbon tests on plants found in the rock to determine its exact age, Hawass said."

It appears from this that the Egyptians are playing the media to get coverage. The expedition is conducting a range of radiometric tests to determine the age, starting with carbon tests like 14C and AMS to rule out/determine a relatively recent age.

Whatever the result, this is going to be a unique find in the context of Eastern Saharan archaeology.